avoid background merge thread stop

Former-commit-id: 7750a6df8cbec3ab3aab090f0c81e641795b9f03

cpp/src/db/DBImpl.cpp

@@ -229,7 +229,6 @@ void DBImpl::BackgroundTimerTask() {
     Status status;
     server::SystemInfo::GetInstance().Init();
     while (true) {
-        if (!bg_error_.ok()) break;
         if (shutting_down_.load(std::memory_order_acquire)){
             for(auto& iter : compact_thread_results_) {
                 iter.wait();
@@ -392,7 +391,7 @@ void DBImpl::BackgroundCompaction(std::set<std::string> table_ids) {
     for (auto& table_id : table_ids) {
         status = BackgroundMergeFiles(table_id);
         if (!status.ok()) {
-            bg_error_ = status;
+            ENGINE_LOG_ERROR << "Merge files for table " << table_id << " failed: " << status.ToString();
             return;
         }
     }
@@ -498,7 +497,7 @@ void DBImpl::BackgroundBuildIndex() {
         /* ENGINE_LOG_DEBUG << "Buiding index for " << file.location; */
         status = BuildIndex(file);
         if (!status.ok()) {
-            bg_error_ = status;
+            ENGINE_LOG_ERROR << "Building index for " << file.id_ << " failed: " << status.ToString();
             return;
         }
 

cpp/src/db/DBImpl.h

@@ -114,10 +114,8 @@ class DBImpl : public DB {
     BuildIndex(const meta::TableFileSchema &);
 
  private:
-
     const Options options_;
 
-    Status bg_error_;
     std::atomic<bool> shutting_down_;
 
     std::thread bg_timer_thread_;